Mercury boiler



June 4, 1940. I CARPENTER 2,202,831

MERCURY BOILER Fi l ed Aug. 17. 1958 L T T L Inventor:

Robert J. Carpenter;

H is Attorney.

Patented June 4, 1940 MERCURY Bonn e Robert J. Carpenter, Scotia, N. Y., assignor to General Electric Company, a corporation. of

New York Application August 17, 1938, Serial 'No. 2 25 ,475

Claims.

The present invention relates to mercury boilers or generally to elastic fluid generators including a drum located inside the boiler and sub- 1 ject to heat from the combustion and convection spaces during operation. Such boilers usually have a plurality of heating elements located in the combustion and convection spaces and arranged to receive liquid from the drum, and to discharge mixture of liquid and vapor or elastic fluid to the drum. In cases in which the drum is of considerable length with its axis horizontallydisposed, it becomes important to reduce the axial or cross flow of liquid inside the drum, especially in the case of mercury boilers because there the axial flow inside the drum may cause considerable level diiferences in the drum due to the high flow resistance of mercury liquid.

The object of my invention is to provide an improved. construction and arrangement of elastic fluid generators, particularly of mercury boilers whereby the aforementioned difiiculties are substantially eliminated.

. For a consideration 'of What I believe to be novel andmy invention, attention is directed to the following description and the claims appended thereto in. connection with the accompany-' ing drawing.

In the drawing, Fig 1 illustrates a sectional view partly broken away of a mercury boiler embodying my invention; and Fig. 2 is a section taken along line 2--2 of Fig. 1.

The arrangement comprises a casing formed by walls l0 and H which have adjacent portions connected by a sliding joint It to permit relative expansion of the walls during operation. The casing forms a combustion chamber IS. A cylindrical drum M is horizontally disposed in an intermediate portion of the combustion chamber projecting through the rear and front walls of the casing and dividing the combustion chamber into a primary combustion space below the drum and a secondary combustion space above the drum. Pairs of horizontal headers 15 and- IG are connected to each side of the drum I4 near the ends thereof. The rear wall of the combustion space below the drum is lined with heating tubes I! connected at their upper ends to the headers l5, l6 and at their lower ends to headers I 8 to which mercury liquid is supplied from the drum by means including down-tubes 20. During operation, mercury liquid is conducted from the drum I l through the downtubes 20 and the headers l8, whence it flows through the up-tubes l1 and is heated therein,

the mixture of mercury liquid and vapor thus formed being discharged into the headers l5, l6 and the drum It; The side walls of the combustion space are lined with heating tubes 2| and 22. The lower ends'of the heating tubes 2| are connected to headers 23, which latter are connected to the aforementioneddown-tubes 2|] to receive mercury therefrom. The upper ends of the tubes 2! which constitute up-tubes with regard to the flow of mercurytherein are bent inwardly and arranged in groupsof twisted or roped tubes 24 connected to the drum M to discharge the mixture of mercury liquid and vapor formed during operation into the latter. The tubes 22 are connected at their upper ends to mercury liquid supply means including headers 25 to receive mercury liquid to be heated from the latter. With regard to the downward direction of the flow through the tubes 22 they may be termed downtubes.' The lower ends of the tubes 22 are bent upwardly and connected to ropes of tubes 26 located above the ropes 24, preferably in staggered relation to the latter, to act as slag screens.

The ropes of tubes'26 extend to a level near the drum and are connected to the lower ends of walls of inclined tubes 21, 28 located in the secondary combustion space and extending along thedrum M. The secondary combustion space also contains down-tubes 29 lining the rear walls and connected at the'lower ends to the headers I5, IS. The side walls of the secondary combustion space are lined with down-tubes 30 which have lower end portions 3| curved inwardly and connected to discharge heated mercury into the drum M. A more detailed description of the heating elements and the general arrangement of the boiler may be found in the application of B. P. ,Coulson, Jr., filed on the same date and assigned to' the same assignee as the present application, Serial Number 225,464. In order to reduce the amount of mercury liquid necessary for operating the boiler and to effect good separation of mercury liquid and vapor inside the drum, it is important to maintain a 10W, substantially uniform mercury level inside the drum. To this end the mercury liquid is discharged from the drum in accordance with my invention by means of a plurality of spaced, substantially vertical conduits or conduit branches 32 connected to the bottom of the drum and discharging the mercury liquid into two conduits 33 and 34 which have outer ends connected to the down-tubes or conduits 20. Each of the conduits 33 and 34 has a plurality of sections 35, 36 with a diameter increasing in the direction of flow, this direction being indicated by arrows (Fig. 2). The conduits and conduit portions 32 to 36 are located below the drum and enclosed by a horizontal channel or casing 31 made of heat insulating and heat resistant material. The casing is substantially triangularly shaped with the point of the triangle pointing downward and the base formed by heat insulating material covering the bottom of the drum I4, thus offering a minimum resistance to the flow of combustion gases from the primary to the secondary combustion space. The casing 31 projects through the entire boiler and is opened in the front and rear as shown in Fig. 2 so that the down-tubes may be readily inspected. Thus, the down-tubes and their connections to the bottom of the drum M are completely protected from the radiant heat in the primary combustion space. The plurality of connecting conduits 32 and the increasing diameters of the sections 35, 36 assure uniform discharge of mercury liquid from the difierent portions of the drum whereby a substantially uniform level is maintained inside the drum and cross-flow, that is, flow of liquid mercury in the direction of the axis of the drum is substantially eliminated. The outer surface of the casing 31 is covered or lined with heating tubes having lower portions connected to the ropes of tubes 24 and upper end portions connected to discharge heated mercury into the drum.

The mixture of mercury liquid and vapor discharged into the drum from the various heating elements is separated inside the drum. The separating device includes a cylindrical segment 38 forming together with the upper portion of the drum an annular channel 39 into which the heated mixture of mercury liquid and vapor is discharged during operation. The mixture flows circumferentially along the channel into a mercury pool. 38 formed on the bottom of the drum, the liquid mercury being recirculated through the down-tubes and the mercury vapor is discharged through a plurality of vapor discharge conduits 4| which are connected to the segment 38 to communicate directly with the space inside the cylindrical segment. The provision of a plurality of discharge conduits 4!, in the present instance four, assures uniform discharge of vapor from the various portions of the drum and also reduces disturbances of the pool which otherwise might occur. The vapor discharge conduits 4! are enclosed by a housing or casing 42 made of heat insulating and heat-resistant material. The walls of this housing converge upwardly to offer minimum resistance to the flow of combustion gases through the secondary combustion chamber. The housing 42 is open at one end, as shown in Fig. 2. The outer surfaces of the housing walls are lined by the aforementioned walls of heating tubes 2?, 28 to protect the housing from heat.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Elastic fluid generator comprising a casing forming combustion and convection spaces, a drum located at least partly within said spaces, heating elements disposed within said spaces and connected to discharge hot fluid to the drum, and means for conducting liquid from the drum to said heating elements, said means comprising a conduit having an upper horizontal portion located in the casing below and in proximity to the drum with a plurality of branches connected to spaced portions of the bottom of the drum and a wall of heat-insulating material below the horizontal portion.

2. In an elastic fluid generator, the combination of a horizontally disposed drum, and means for discharging liquid from the drum comprising a conduit located below the drum and having a plurality of branches connected to separate portions along the bottom of the drum, the conduit having a diameter increasing in the direction of flow of liquid therethrough in order to effect uniform discharge of liquid from the various portions of the drum and substantially to eliminate cross-flow Within the drum.

3. A mercury boiler comprising walls forming a combustion chamber, a drum supported on the walls and projecting into the chamber, a horizontal heat-insulated channel formed below the drum and communicating with the atmosphere, heating elements located in the chamber and having discharge ends connected to the drum, and means for conducting liquid from the drum to the inlets of the heating elements comprising a conduit having an upper portion substantially horizontally disposed in the channel with branches connected to spaced bottom portions of the drum to effect complete mixing of liquid from several portions of the drum before the liquid is admitted to any of the heating elements.

4. A mercury boiler comprising walls forming a combustion chamber, a drum supported on the walls and projecting into the chamber, heating elements located in the chamber and having dis charge ends connected to the drum, means for conducting liquid from the drum to the inlets of the heating elements comprising a conduit having a portion substantially horizontally disposed below the drum with branches connected to spaced bottom portions of the drum, said conduit portion having a diameter increasing in the direction of flow of liquid therethrough, and means protecting said conduit from the heat in the combustion chamber comprising a casing partly formed by the drum and enclosing the conduit portion with its branches.

5. A mercury boiler comprising a casing forming a combustion chamber, a drum supported on the casing and projecting through the chamber and dividing it into a primary combustion space below the drum and a secondary combustion space above the drum, heat insulating material covering the drum within the chamber, means including a plurality of conduits connected to axially spaced bottom portions of the drum for uniformly discharging mercury liquid from the various portions of the drum, and means for protecting said conduits from the heat in the chamber comprising a triangularly-shaped casing with a base formed by the drum and pointing downwardly thus reducing the resistance of the flow of combustion gases from the primary to the secondary chamber, said protecting casing extending horizontally through the boiler casing and being open at its ends to permit inspection of the conduits during operation.

ROBERT J. CARPENTER. 

